Apparatus and process for concentrating argon.



G. R. FONDA.

APPARATUS AND PROCESS FOR CONCENTRATING ARGON.

APPLICATION FILED OCT. I2. 19I5.

Patented Jan. 2, 1917.

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GORTON R. FOllIDA, OF SCHENECTA-DY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

T atinas.

.The present invention;relates to the separation of argon in the rectification or frac- 1 tional distillation of liquefied air.

It has been suggested to produce commercial argon by conducting a gaseous mix tureof-oxygen, nitrogen, and argon, ob-

tained bythe partial liquefaction and rectification of air, into a zone maintained at a temperaturelow enough to condense most of the oxygen, leaving a gas rich in argon and containing oxygen and nitrogen.-

. In accordance with my invention, T have provided a more eflicient apparatus and method for separating argon. As hereinaf- I ter more fully described, ordinary liquid air is first rectified with the removal of I nitrogen until a liquid residue is obtained containing about 94-. to 96% oxygen, several per cent. of argon and incidentally some nitrogen. This liquid oxygen-argon mixture, instead of a gaseous mixture, as formerly suggested, is rectified to produce com -mercially pure oxygen and the gases derived from the rectification are conducted to a zone maintained at a temperature 7 low enough to condense oxygen. The uncondensed argon from this zone is carried away for use and the liquid condensate is returned to the rectification column in contact with the vapor from said column.

The accompanying drawing illustrates somewhat diagrammatically one emiment of my invention.

The apparatus includes a laterally ninclosed tectification column 1 (shown on the right-hand side of'the drawing) wherein the liquid air is received and submitted to tractional distillation and a rectification column 2 (shown on the left-hand side of the drawing) whereinthe mixture of liquid oxygen and liquidfarglon is further rectified. Air compressed to about 7 0 atmospheres is supplied by a pipe 3. At the beginning ofthe operation of the device the valve 4 in the pipe 5 is closed, the valve 6 being open. The compressed air asses through a coil lv at the foot of the co umn 1 where it is sur- Specification of Letters Patent.

APPARATUS AND PROCESS FOR GONCENTBATING ARGON.

Patented Jan. 2, rear.

Application filed October 12, 1915. Serial No. 55,399.

rounded by and boils liquefied air which may be supplied at this-point in any way at the beginning of the operation. The cooled compressed air mixed with liquid formed in pipe 7, is carried away by a pipe 8'to an expansion valve 9 where the non-liquefied air is liquefiedin the usual well understood manner by the refrigerating effect of expansion, and the temperature of the liquid is lowered to a point corresponding to the lower pressure. The liquefied air is discharged by a pipe 10 to the top of the column' 1 and descends through the perforated plates 11 where it comes in contact with the ascending vapors from the liquid collecting at the foot of'the column. The oxygen and argon in the ascending vapors are condensed and the nitrogen in the descending liquid correspondingly vaporized, commercially pure nitrogen escaping from the top of the column from a pipe 12 and a liquid consist ing largely of oxygen and containing most of the argon collecting at the foot of the column 1. This liquid being boiled by the warmer compressed air in the coil 7, and thereby losing nitrogen, the more volatile constituent becomes constantly richer in oxygen and argon. When this liquid contains about 94 to 96% oxygen the valve 13 in the pipe 14 is opened. The pressure of-the vapo'rjn the column 1 forces the liquid surrounding the coil 7 over into the column 2 perforated plates. 15. The gas at the foot of the column, being commercially pure oxygen, is carried away by the pipe 17. The ascending vapors now richer in argon than the liquid supplied by the pipe 14.- pass into a cooling spiral 18, terminating in a container 19. The spiral and the containerare surrounded by a cooling liquid cold enough to condense oxygen. Conveniently this liquid is constituted by liquid air supplied "from the liquefier by closing the valve 20 and opening the valve 21. The liquid air is conducted through the pipe 22 to the tank 23 and overflows through the pipe 24: to the discharge pipe 10. The liquid condensed inthe spiral 18 and the chamber 19 which is largely oxygen and contains also some argon part of the tower 23 is reduced to such a.

point that the gas coming off through the pipe 25 can be collected for use as argon concentrate. It contains about argon, 40% oxygen and 20% nitrogen.

lVhat I claim as new and desire to secure by Letters Patent of the United States, is

1. Means for fractionating a mixture of liquid oxygen and argon comprising the combination of a rectification column, means for introducing said mixture at an intermediate point in said column, means for evaporating liquid at the foot of said column, a conduit for withdrawing gas at the foot of said column, means for refrigerating the gaseous mixture at the top of said column to the liquefying temperature of oxygen, means for returning the condensate to said column and means for conducting away the uncondensed gases rich in argon from the top of said column.

2. The process which consists in boiling a mixture comprising a liquid oxygen and argon, introducing fresh portions of said liquid in contact with the ascending vapors from said liquid, withdrawing oxygen near the. surface of said liquid, refrigerating the vapors at a region above the point-of introduction of said liquid to condense oxygen,

'3. The process of fractionating liquid'air which consists in rectifying said liquid air until a liquid containing about 94% oxygen and several per centaargon is obtained, con-c ducting said liquid into a vertically-extending confined space, collecting and evaporating liquid at the foot of said space, conduct= ing away gaseous oxygen from the foot of said space, conducting the rest of the gaseous mixture in contact with the descending liquid mixture thereby evaporating argon from the descending liquid-and liquefying oxygen from the ascending gas, refrigerating the ascending gases at a point higher.

than the point of introduction of the liquid mixture to condense oxygen, conducting away a gaseous argon residue and returning the condensed liquid in contact with ascending gases to the foot of the confined space.

4. The process of concentrating argon which consists in fractionating liquid air until a liquid residue is obtained containing about 94% oxygen and about 4% argon, withdrawing said liquid and subjecting the same to counter-current rectification, conducting the vapor to a refrigerating zone maintained at a temperature lower than the boiling point of oxygen, conducting away the uncondensed argon and returning the condensate to the rectification zone, in contact with the "vapors being conducted to the refrigerating zone.

In witness whereof, I have hereunto set my hand this 11th day of October 1915.

GORTON R. FONDA. 

